Lead Free Monobloc Expansion Projectile and Manufacturing Process

ABSTRACT

The present invention relates to a bullet made of a single solid piece of deformable metal, containing no lead or toxic material, easily deformable but without fragmentation in a soft environment with a high rate of energy transfer, and a high level of solidity in hard targets, retaining most or its total initial weight while penetrating those targets. Said objects are achieved by constructing a solid monobloc bullet with a cavity on the longitudinal axis which is opened towards the fore end of the bullet. The method of construction encompasses a sequence of simple operations: cutting of a cylinder blank of soft material, forming a cavity centered on the longitudinal axis, and forming an ogival or conical form, with external pre-cuts to foster an homogenous deformation. The present invention applies to any handgun, rifle or shotgun ammunition; when used in smoothbores, the essential stability of the bullet is achieved by positioning the center of gravity ahead of the aerodynamic cent

BACKGROUND OF THE INVENTION

It is recognized today that the use of lead or other toxic material in a bullet constitutes a great nuisance for the environment and the user, and must therefore be avoided.

It is also well know that projectiles, particularly those used in police operations or personal defense, must feature a high capability for stopping an attacker at once, without traversing the target and thus perhaps wounding other people. That is particularly important when the use of said ammunition is considered under extreme situations, such as those involving life risk for the police officer, an innocent pedestrian, etc.

These projectiles, used in police operations, must be able to pass through tactical obstacles that offer protection to the criminal such as vehicle doors or windscreen. However, the projectile must be able to do it without changing it's trajectory, lest there is serious risk of injuring innocent people which are not being targeted by police action.

DESCRIPTION OF RELATED ART

Projectiles deforming on impact have been known for a long time, and were initially made of lead, usually with a hollow point. Nowadays these projectiles are made of solid materials, and are generally composed of two pieces, with the fore piece generally made of plastic, or sometimes metal acting as a pusher to create expansion. Examples of said projectiles in the state of the art can be found on “REDUCED-CONTAMINANT DEFORMABLE, BULLET, PREFERABLY FOR SMALL ARMS” by Knappworst et al. (WO 01/67030 A1); “SMALL-CALIBRE DEFORMATION PROJECTILE AND A METHOD FOR THE PRODUCTION OF THE SAME”—Baumgartner et al. (WO 01/88460 A1); “DEFORMATION PROJECTILE”—Sigl et al. (WO 01/02791 A1); “Projectile Pour Armes à Feu Notamment Pour Armes de Poing et armes à canon long”—A Dynamit Nobel (FR 2369538); “Jacketless hunting bullet with roll-back cutting flags”—A Avcin (U.S. Pat. No. 4,044,685); “Cartridge for hand and shoulder firearms”—Schirnecker (U.S. Pat. No. 4,136,616 A); “DEFORMATION PROJECTILE”—DNAG (WO 01/02791 A2); “PROJECTILE”—Winter (U.S. Pat. No. 5,160,805), “Projectile with improved flowering”—Petrovich et al. (U.S. Pat. No. 5,185,495)).

Another type of solid monobloc projectile operation is based on the internal geometry of the bullet cavity, which features a shape resembling a star, or another specific geometry which performs the same way. These can be found on “Methods of manufacturing a bullet”—Brooks (U.S. Pat. No. 5,131,123) and “Intermediate article used to form a bullet projectile or component and a finally formed bullet”—Brooks (U.S. Pat. No. 5,259,320).

Another type of solid monobloc projectile is a single piece solid, without cuts or cavities, generally for big game hunting, featuring maximum penetration. Examples of these are found on “Solid projectiles”—Lufty (U.S. Pat. No. 4,811,666) and “Projectile”—Hatcher (U.S. Pat. No. 2,234,165). These projectiles feature very little expansion.

Yet another type of solid monobloc projectile operates by means of an internal cavity with a central pin or axis, being the external portion of the bullet provided with grooves to generate the targeted expansion. An example would be “EXPANSION PROJECTILE”—Winter (WO 97/40334).

The Inventor chooses to make no comments here on the classic hollow point projectiles composed of a core and a jacket, which lie outside the scope of the present invention.

SUMMARY OF THE INVENTION

The present invention can be better understood by analyzing the specification text along with the attached set of Figures, in which:

FIG. 1 a shows a typical example of a projectile described in the present invention, which general external shape include a main cylindrical portion, a front portion of generally ogival shape and a rounded bottom portion, the same FIG. 1 a is used to illustrate the projectile's longitudinal section, with an internal cavity of substantially elliptical shape. In this example, the largest cross-sectional diameter is situated between the front open portion of the projectile and the bottom of the internal cavity, being said bottom a flat surface. This same FIG. 1 a is used to illustrate one of a plurality of external deformations with the form of grooves that extend externally from the front end of the projectile. The purpose of said plurality of grooves is to facilitate the expansion or mushrooming of the projectile.

FIG. 1 b shows a typical shape of an alternative projectile, with a front portion of truncated conical shape, and a cavity with a generally rounded bottom shape, being the remainder portions of this projectile identical to their analogs of FIG. 1 a. It is always worth to remember that both FIG. 1 a and FIG. 1 b are given solely as non-limitative examples.

FIG. 2 a is a front view illustrating a typical projectile with axially symmetrical shaped cavity (hexagonal shape in this example).

FIG. 2 b a front view illustrating a typical projectile with axially symmetrical shaped cavity (hexagonal shape in this example).

FIG. 3 shows a typical intermediate shape of a metal piece illustrating its appearance after the first cold forming operations of the manufacturing sequence with a typical example of cavity with a cylindrical portion, a generally conical/elliptical portion and a generally flat bottom portion.

FIG. 4 illustrates parts of a typical manufacturing sequence, showing successively:

Copper or copper alloy cylinder after cutting a wire or rod; copper or copper alloy piece after first cold deformations; initial projectile ogive or conical fore portion forming and external grooves forming; final fore portion forming; the calibration, annealing, and surface finishing do not change the general form of the bullet.

It is worth observing that all shapes and geometries described herein refer to both the internal and external geometries.

One of the objects of the present invention is to disclose a projectile that easily and quickly deforms upon expansion after penetrating soft targets, generating an expansion of at least 40% compared to the puncture diameter measured on the initial impact surface, with no loss of original weight, no breakage of the projectile, performing a fast transfer of energy in the early portion of the trajectory inside the soft environment, and avoiding unintentional hits on secondary targets.

Another object of the present invention is a projectile that easily perforates hard targets without breaking or changing its trajectory.

Another object of the present invention is a projectile that contains no lead or other hazardous material.

Another object of the present invention is a projectile which homogenous construction allows high performance in the aspect of accuracy.

Yet another object of the present invention is a projectile easy to manufacture at a reasonable cost, with existing manufacturing tools and technology.

The present invention applies to any handgun, rifle or shotgun ammunition; when used in smoothbores, the essential stability of the bullet is achieved by positioning the center of gravity ahead of the aerodynamic center.

The present invention attains the objects described above through the combination of characteristics which are discussed in the following paragraphs.

Material:

The present invention discloses a solid projectile (made of one single piece) of a material which density preferably ranges from 6 to 10. Said material is preferably copper or a copper alloy, with a Vickers hardness preferably ranging from 40 to 70.

Internal Cavity:

The projectile features an internal cavity centered regarding the longitudinal axis of construction. The longitudinal section of said cavity preferably presents a generally elliptical shape, with or without a cylindrical portion interspersed. In order to describe the shape of said internal cavity, the Inventor chose to use a radial coordinate system, in which (r) is the radius of a circumference which is normal to the longitudinal axis of the projectile and (d) is the abscise of a generic point which lies in said longitudinal axis of the projectile. The various values assumed by (d, r) describe successive circumferences (all of them normal to the longitudinal axis of the projectile) which make up the perimeter of the internal cavity. The origin adopted for said coordinates system is the point of the longitudinal axis of the projectile which lies in the same plan that contains the forward most section of the projectile (i.e. the front end of the projectile, where d=0).

For instance, the maximum value of (d) corresponds to the bottom of the internal cavity.

The ideal proportions for the internal cavity of the projectile of the present invention are defined regarding the caliber of said projectile, being the caliber defined by the diameter of the cylindrical portion of the projectile:

the maximum value of r is situated between the positions where the value of d=0 and d=d_(maximum);

said radius r decreases progressively towards the front end where d=0;

said radius r decreases progressively towards the bottom of the cavity where d=d_(maximum);

where d=0 (front end of the projectile) said radius r ranges from 10% to 40% of the caliber of said projectile;

the maximum value of said radius r of said internal cavity ranges from 10% to 40% of the caliber of the projectile;

where d=d_(maximum) (bottom of the cavity) said radius r ranges from 0 (flat surface) to 35% of the caliber of said projectile (rounded bottom);

d_(maximum) ranges from 0.50 to 2.5 times the caliber of said projectile;

the transversal and longitudinal cross-sections of said cavity present radial symmetry regarding the longitudinal axis of said projectile, being said cavity cross-section of a circular or other regular geometrical figure shape.

External Grooves:

The projectile of the present invention features a plurality of grooves, slits or other geometrical forms that extent longitudinally over the external face of the projectile. The purpose of said plurality of grooves is to facilitate the opening of the projectile and avoid breaking. The number of grooves or slits preferably ranges from 3 to 9. The cross section of said grooves is preferably of a generally triangular shape, and their length is preferably superior to 5% of the length of the internal cavity.

Said grooves or slits extend from near the front end of the projectile to a maximum length where the cross-section where is located the crimping or the case mouth. Let us remember that the bullet is mounted to a case containing propulsive powder and primer, being said case crimped to the bullet in order to hold it in place, and said crimping forming a generatrice on the cylindrical portion of the bullet.

Bottom Portion of the Cavity:

The bottom portion of the central cavity is either a three-dimensional rounded end or a plan surface with circular perimeter, that being described by the values of (r, d) for the region of the bottom of the cavity.

These characteristics of solid monobloc construction, suitable material and hardness (copper or copper alloy and final annealing to obtain a Vickers hardness of 40 to 70), geometry of the internal cavity and the external grooves are responsible for the outstanding performance of the present invention. The bullet will nor break, even upon hitting hard targets such as a safety glass or multiple sheets of steel; the bullet will rapidly mushroom or expand and thus is able to generate a rapid transfer of energy into soft targets.

Manufacturing Sequence

The bullet of the present invention can be constructed following this general manufacture sequence:

a) Cutting of a proper cylinder blank, preferably by cutting, sawing or shearing a wire or rod of suitable material, such as copper or copper alloy.

b) Cold forming of a preliminary internal cavity centered on the longitudinal axis of said cylinder blank, were the geometry of said cavity is roughly equal to that of a cylinder in which the radius varies a little along certain portions of its length. Said preliminary internal cavity may or may not include a portion of pure cylindrical shape (r=constant), and the bottom of said cylinder may correspond to a section of a sphere (r progressively diminishing towards the bottom of the cavity) or a sheer plan surface (r abruptly made=0). The shaping of the preliminary internal cavity is controlled by simply varying the values of (r, d) of the punch used in the cold forming according to the desired shape of the cavity. Said cold forming involves one or more strikes of suitable punches on the chosen end of the cylinder blank obtained on the previous cutting step creating a deformation axially symmetrical to the longitudinal axis of said cylinder blank, said obtained final deformation forming a preliminary internal cavity presenting a larger radius r toward the front end of the projectile where d=0 is zero, with the radius r of said internal cavity varying preferably as:

the maximum value of radius r of said internal cavity is situated where d=0, ranging preferably from 95% to 70% of the radius of said cylinder blank;

With a cylindrical portion, situated between the front end and the bottom of the cavity, the length of said cylindrical portion ranging from zero to twice the diameter of said cylinder blank;

The radius r of said internal cavity decreasing from where d=0 to d=d_(maximum) where the radius r ranges from 35% of the diameter of said cylinder blank to r=0;

The maximum value of d ranges from 0.50 to 2.5 times the diameter of said cylinder blank;

c) Formation of the external deformations of the form of grooves, preferably by pressure applied with the appropriate tool or die.

d) Shaping of the end of the ogival nose portion;

e) Calibration of the caliber diameter, made by forcing the projectile through a cylindrical cavity tool;

f) Annealing to the suitable hardness, if necessary;

g) Application of a superficial finish such as polishing (preferably by trammeling), plating with a suitable material, covering (preferably by spraying or dipping in a suitable polymeric material), etc.

Those skilled in the art will realize that the operations encompassed on steps c) to g) can be performed using methods belonging to the current state of the art, and that the description of one or more of the preferential incorporations of the present invention does not limit its scope of application, which is in fact limited only by the set as defined in claims attached herein. 

1. An expansion projectile for firearms, comprising one single piece of material from the copper class, or copper alloy, presenting a generally cylindrical shape with a fore portion generally of conical or ogival shape, and a bottom portion with a rounded or truncated conical portion; said projectile featuring an internal cavity opened towards the front end of the projectile, being said cavity symmetrically centered regarding the longitudinal axis of the projectile; being the radius (r) descriptive of a circumference that establishes a circular cross section perpendicular to the central longitudinal axis of the projectile and (d) descriptive of the abscises of a generic point which lies in said longitudinal axis of the projectile, being the shape of the internal cavity of the projectile described by the values of (r, d) taking as origin for said coordinates system the point of the longitudinal axis of the projectile which lies in the same plan that contains the forward most section of the projectile, with d=0 corresponding to the front end of the projectile and the maximum value of d corresponding to the bottom of the cavity; characterized by the fact that the maximum value of r is situated between the positions where the value of d=0 and d=d_(maximum); said radius r decreases progressively towards the front end where d=0; said radius r decreases progressively towards the bottom of the cavity where d=d_(maximum); where d=0 (front end of the projectile) said radius r ranges from 10% to 40% of the caliber of said projectile; the maximum value of said radius r of said internal cavity ranges from 10% to 40% of the caliber of the projectile; where d=d_(maximum) (bottom of the cavity) said radius r ranges from 0 (flat surface) to 35% of the caliber of said projectile (rounded bottom); d_(maximum) ranges from 0.50 to 2.5 times the caliber of said projectile; the transversal and longitudinal cross-sections of said cavity present radial symmetry regarding the longitudinal axis of said projectile, being said cavity cross-section of a circular or other regular geometrical figure shape.
 2. The expansion projectile as defined in claim 1, in which the external surface features a plurality of lengthwise grooves or slits parallel to the central longitudinal axis of the projectile and symmetrically distributed around it, being said grooves or deformations obtained by pressure forming, when the fore portion is partially closed in a die to form the generally conical or ogival shape of the fore portion of projectile; being said grooves or slits preferably provided in a number of 3 to 9, extending longitudinally from the front open end to the generatrice where the case mouth is crimped; being said projectile characterized by the fact that the total cross sectional area of said grooves or slits ranges between 0.2 and 5% of the total cross sectional area of the projectile; said grooves or slits preferably featuring an essentially triangular cross-sectional shape; and being the length of the said grooves preferably more than 5% of the length of the internal cavity of said projectile.
 3. The expansion projectile as defined in claims 1 or 2, characterized by the fact that the internal cavity is obtained by means of cold forming a raw material cylinder blank obtained by cutting a wire or rod preferably by shearing of suitable material, such as copper or copper alloy, applying a single or more strikes of suitable punches on the cylinder blank creating a deformation which is axially symmetrical to the longitudinal axis of said cylinder blank, said obtained final deformation forming a preliminary internal cavity presenting a larger radius r toward the front end of the projectile where d=0 is zero, with the radius r of said preliminary internal cavity varying preferably as: the maximum value of radius r of said preliminary internal cavity is situated where d=0, ranging preferably from 95% to 70% of the radius of said cylinder blank; With a cylindrical portion, situated between the front end and the bottom of the cavity, the length of said cylindrical portion ranging from zero to twice the diameter of said cylinder blank; The radius r of said preliminary internal cavity decreasing from where d=0 to d=d_(maximum) where the radius r ranges from 35% of the diameter of said cylinder blank to r=0; The maximum value of d ranges from 0.50 to 2.5 times the diameter of said cylinder blank.
 4. Manufacturing process for the expansion projectile as defined in claims 1, 2 or 3, being said final operations finishing and adjusting operations, respectively finishing the shape, calibration, annealing and superficial finishes, that are performed in a way that is well known by those skilled in the art of ammunition manufacturing; being said manufacturing process characterized by the fact that the manufacturing sequence comprises the following successive steps: generation of a cylinder blank of proper weight and diameter by means of cutting, sawing or shearing a wire or rod of suitable material, preferably copper or a copper alloy; cold forming by one or more strokes with punches of single or progressive circular or polyhedric cross-section hitting the cylinder blank positioned in a die, totally or progressively creating a preliminary internal cavity without altering the external cylindrical shape of the metal piece; execution of a plurality of grooves or slits and preliminary shaping of the fore portion of the projectile, thus modifying the radius of the cavity obtained on step b above and reducing this radius by at least 7%, and modifying the shape of the preliminary internal cavity by displacement of the main diameter from the front end to a position between the front end and the bottom of the cavity. 